linux I2C 读写 tlv320dac3100

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <linux/i2c.h>
#include <linux/i2c-dev.h>

#define DAC3100_DEV  "/dev/i2c-2"
#define DAC3100_ADDR 0x18

static unsigned char g_page = 0xFF;

void dac3100_change_page(int fd, unsigned char page)
{
    int err;
    struct i2c_rdwr_ioctl_data data;
    struct i2c_msg msg;

    if (g_page == page) {
        return;
    }

    data.nmsgs = 1;
    data.msgs  = &msg;
    msg.addr  = DAC3100_ADDR;
    msg.flags = 0;
    msg.len   = 2;
    msg.buf   = (unsigned char*)malloc(2);
    msg.buf[0] = 0;
    msg.buf[1] = page;

    err = ioctl (fd, I2C_RDWR, (unsigned long)&data);
    if (err < 0) {
        printf("ERR: I2C_RDWR => %d\n", err);
    }
    g_page = page;
    free(msg.buf);
}


unsigned char dac3100_read(int fd,
        unsigned char page,
        unsigned char reg)
{
    int err;
    struct i2c_rdwr_ioctl_data data;
    struct i2c_msg msg[2];

    unsigned char rst;
    dac3100_change_page(fd, page);
    
    data.nmsgs = 2;
    data.msgs  = msg;
    msg[0].addr  = DAC3100_ADDR;
    msg[0].flags = 0;
    msg[0].len   = 1;
    msg[0].buf   = ®
    msg[1].addr  = DAC3100_ADDR;
    msg[1].flags = I2C_M_RD;
    msg[1].len   = 1;
    msg[1].buf   = &rst;

    err = ioctl(fd, I2C_RDWR, (unsigned long)&data);
    if (err < 0) {
        printf("ERR: DAC3100 READ => %d\n", err);
    }

    return rst;
}

int main(int argc, char** argv)
{
    int fd, err;
    int page, reg, pcnt = 3;
    unsigned char pages[] = {0, 1, 3};

    fd = open(DAC3100_DEV, 0, O_RDWR);
    if (fd < 0) {
        printf("ERR: device open failed!");
        return -1;
    }

    err = ioctl(fd, I2C_TENBIT, 0);
    if (err < 0) {
        printf("ERR: IOCTL I2C_TENBIT => %d\n", err);
    }

    for (page = 0; page < pcnt; page++) {
        printf("------- PAGE %d -------\n", pages[page]);
        for (reg = 0; reg < 128; reg++) {
            printf("%02X ", dac3100_read(fd, pages[page], reg));
            if ((reg % 8) == 7) {
                printf("\n");
            }
        }
    }


    close(fd);
    return 0;
}